1. Field of the Invention
The present invention relates to power supply circuits and, particularly, to a power supply circuit for a motherboard in a computer.
2. Description of the Related Art
In electronics and particularly in computer electronics, motherboards are one of the most important parts. Power supply circuits are used to provide working voltages for motherboards, and are absolutely necessary, especially for the north bridge. A digital to analog converter A (DACA) analog output pin, herein called a DACA VDD pin, of the north bridge provides a DACA VDD signal to control a vertical synchronization (VSYNC) signal and a horizontal synchronization (HSYNC) signal output from the north bridge to a display. However, a conventional power supply circuit includes an inductor-capacitor (LC) oscillating circuit for providing power to the DACA VDD pin. But sometimes, the power provided to the DACA VDD pin is unstable, which can adversely affect the VSYNC signal and HSYNC signal and cause ripples in the display.
What is needed, therefore, is to provide a power supply circuit for a motherboard which can provide stable power to the north bridge.